1. Technical Field
The technical field relates to a carbon material for a power storage device. More particularly, the technical field relates to a carbon material for a power storage device electrode which is used as an electrode active material such as for a sodium-ion rechargeable battery.
2. Description of Related Art
In recent years, power storage devices have been used in, for example, mobile apparatuses such as mobile phones, and electric cars. In addition, clean energies such as photovoltaic power generation have been increasing sought. As a result, large-scale power storage facilities are required for stabilization of electric power production and supply, and demand for power storage devices is continuously expanding.
For these purposes, large-capacity power storage devices are required, and lithium-ion rechargeable batteries have actively been developed.
Meanwhile, rare metals such as lithium, nickel and cobalt are used as cathode materials in lithium-ion rechargeable batteries. However, rare metals are limited resources. Therefore, in recent years, development of sodium-ion rechargeable batteries which do not include rare metals in cathode materials has been studied.
However, since the ion radius of sodium ions is larger than that of lithium ions, sodium-ion rechargeable batteries cannot obtain sufficient properties if they have the same constitution as that of lithium-ion rechargeable batteries. Therefore, components suitable for sodium-ion rechargeable batteries have been developed.
Among them, anode materials are one of important components which determine charge/discharge properties of batteries. As a conventional carbon material for a power storage device, a vitreous carbon material which exhibits superior charge/discharge properties can be mentioned (for example, see JP-A-2009-129741).
In addition, as a conventional method of producing such vitreous carbon material, a method in which thermosetting resin fibers are subjected to a heating carbonization treatment and an activation treatment, and are then pulverized, can be mentioned (for example, see JP-A-2006-131452).